The importance of computer networks in day-to-day business operations has become a fact of life for many enterprises. The ability of an enterprise to effectively manage the resources of a computer network becomes increasingly important to the enterprise as its use of the network intensifies and as the network itself becomes larger and more complex.
The need for effective network management is most apparent for a large network consisting of individual computer systems or nodes interconnected through communication links. The topology or configuration of such a network typically changes constantly as nodes and/or links are added or dropped.
Because the network itself changes dynamically, a network manager should be capable of responding dynamically to changes in the network when providing management services. A suitable type of network manager is shown in U.S. Pat. No. 4,995,035, issued Feb. 19, 1991, and assigned to the assignee of the present invention.
According to the teachings of this patent, nodes in a computer network are classified either as: (1) control nodes, called focal point (FP) or server nodes; or (2) managed nodes, called non-focal point (NFP) or served nodes. Focal point or server nodes are nodes capable of providing management services to other nodes in the network. One example of such management services is the reception and handling of Alerts, which are messages indicating an event (typically an error event) occurring somewhere in the network. A network which implements the focal point/non-focal point concept is sometimes referred to as a focal point network even though every node in the network is not necessarily a focal point.
A server/served relationship may be established at the request of either of the two potentially-paired nodes. For example, node A may offer to provide a particular management service to node B. If node B accepts the offer, the server/served relationship is established for the particular management service covered by the offer. Alternatively, node B may ask node A to provide a particular management service. If node A accepts, the same server/served relationship is established.
The server/served relationship can also be described as a nested/nesting relationship. Any node which receives a management service from another node is referred to as a nested node with respect to that service. The node that provides the service is referred to as the nesting node.
For any given service, the same node may act both as a server node and as a served node relative to the different nodes with which it is paired. Thus, a given node A may provide Alerts services to a second node B while concurrently receiving Alerts services from a third node C. In fact an entire chain of nodes can exist where all of the intermediate nodes provide a management service to the next node in the chain while receiving the same service from the previous node in the chain.
Once a server/served relationship is established between two nodes, management service data originating at a served node is forwarded on an unsolicited basis to its server node. If a node which receives such data from an originating node is itself also a served node relative to a different server node, it will also forward the management service data to its own server node. Management service data can propagate along an entire chain of nodes.
Allowing two nodes to decide independently of any other nodes whether one will provide management services to the other provides considerable flexibility in determining by whom and to whom necessary management services will be made available. Unfortunately, it can also lead to problems.
If a node at one end of a chain of nodes contacts or is contacted by the node at the opposite end of the chain, a server/served relationship may be set up between those two nodes without regard to the fact the nodes are at the opposite ends of a chain. If that happens and each of the other nodes in the chain has a particular relationship relative to the other two nodes with which it is paired, a closed or continuous loop will be formed.
Management service data originating at any node in the loop will will automatically be passed around the loop from each served node to its server node. Since there is no "end" to the loop, the same data will eventually return to the originating node and thereafter continue to flow around the loop. It goes without saying that continuous circulation of old data through multiple nodes in a computer network isn't viewed as a productive use of the network's resources.